Telephone system



a 1192"" A mg 16g 49 A,'WASCHNACK TELEPHONE SYSTEM Filed'May 22, 1924 OPUIF W Patented Aug. 16, "192 7.

UNITED STA. ES PATENT OFFICE.

non wascmucx, or man 'rmxnnxnue, GERMANY, ASSIGNOR 'ro-smms & men: ax'rmnensnnnson'ar'r, wmmnnwnnx, or smmnnss'mnr, NEAR Ban-- Lm, eaamm.

; 'ITELEPHONE .sxs'rmr.

HEI'SSUED Application flled m 22, 1924, Serial no. 714,998, and in Germany September 20, 1923.

The invention relates to a circuitv arrangement for private branch exchanges with automatic working, in which local and main exchange calls are set up over separate 5 connecting devices.

The invention consists in that main' exchange calls are established by first setting on a particular contact the switches used for local calls and then over this contact operating further switching devices, which mark the calling line in'the bank of the switches associated with the exchange lines and start up the switch of a free exchange line in order to set it on the marked contact. The drawing shows one-method of carrying out the invention and for the sake of clearness, all parts that-do not form part of the invention have been omitted.

An extension station N of a private branch nection over lines such as HL used only for local calls or an outside connection. over lines such as AL used only for main ex change calls. The starting up of a switch such as AW used for exchange calls may be efl'ected over the lines used for local calls and over the connecting devices such as the local switches AS and LVV. The starting up of a main exchange switch and its setting on a calling line is dependent on the switch LW being set on a particular contact of its bank, whereby the relays Anl and K are operated. Thereupon the rotary magnet D of a free mainexchange switch is connected connected up disconnects the leads used for the local trafiic andemployed for initiating the' exchange call; hence the connecting devices AS and LVV arereleased and are again rendered available for the local traffic. The relay S is energized by feed current passing over the subscribers line and extends the call to the main exchange. The incoming calls are handled in known manner at the P. B. X. operators position. In order to deal with an incoming call, the operator connects her head set AbA to the line and by means of exchange HZ can at will set up a local conthe key NT associated with the wanted station, she, marks, the wanted line and starts up an idle exchange switch, for example AW, which is then set on the marked line.

. The method of operating is as follows:

Assume for ,example that a subscriber of the private branch exchange HZ, for instance at the extension station N, wishes to make an exchange calland for this-pun pose takes down his receiver. The following circuit is thereupon completed: earth, winding of the relay An, contact 1t, lead 4:, con-, tact 2t1, extension station N, contact 3751, lead 5, contact 6t, winding of the relay T, battery, earth. Belay T, which is a two step relay, energizes part way and closes its contact 7?? in order to mark the calling line in the bank of the call seekers such as AS. The energizing of they relay An; in this circuit causes an idle call seeker, for instance AS, to be started up in known manner and position on the calhng line 4, 5. After the call seeker AS has reached the calling line, the relay T becomes fully energized due to current supplied over test wiper 9 in known manner, opens its contact-s 1t and 6t, disconmeets the relay Ah which stops the switch, and at 76; is itself held up to hold the call seeker in the set position. The positioning of AS also caused the relay A to be energized over the leads 1-0, 11, thereby closing its contact 12a. The calling subscriber now operates his number dial (not shown), thereby positioning the 'final selector LW on' the selected contact, for instance 13, in its bank. The following circuit is then established: earth, battery, winding I of relay Anl, lead 14, contact 13, Wiper of LW, lead 10, wiper of AS, lead 4, contact 2t1, extension station N, contact 3t1, lead 5, wiper of AS,-, lead 11, wiper of LVV, lead 15, winding II .of the relay Anl, earth. The relay Anl operates in this circuit and at its contact 16(m1 itcloses a circuit for the relay K: earth, winding III of Anl, contact 16cm1, back contact 17 p, winding of K, battery, earth. The relay K operates and at its contact 18k it closes the circuit of the rotary magnet D of an idle main exchange switch, for example Al/V: earth, relay interrupterRU, rotary magnet D, back contact 19p, contact 1870, resistance W, battery, earth.- The-positioning-of LW on the particular contact in its bank also closed-the following circuit for the relay U: earth, front contact 12a, winding of the re- 9 lay U, wiper of LW,contact 13, lead 21,

' as follows: earth, battery, resistance W, contact 18%;, windings II and Iof P, wiper of AW, winding I of the slow acting relay T1,

. wiper 23 of AS, contact 2210, earth. The

relay P also closes its contacts 25p, 26;), thereby energizing the relay S owing to the loop completed over the speakingdeads 27, 28 and 29, 30. The relay S closes its contacts 31s and s. The relay T1, which was likewiseenergized in the test circuit, closes its contact 32t1, thereby establishing a looking circuit for. T1 and P, which extends over the contacts 32t1, 24;), 318. By the energizing of T1, the contacts 2t1 and 32.1 were also opened, thereby the switches AS and LW used for the local P. B. X. trafiic are released and the opening of the contact 17p also effects the release of the relays Anl and K. After the contact 2211 has been opened, the test relay P and the cut off relay T1 are "maintained energized over the before mentioned holding circuit. The calling subscribers extension station N is marked engaged to a final selector set on this line,

because T is maintained energized over the contact 32t1. At the private branch exchange the calling subscribers'lamp ND is connected up over the contact 33t1 of T1 (earth, contact 33t1, lamp NL, battery, earth) and the lamp BL of the exchange line AL taken into use is connected up over the contact 34p of P, thus the P. B. operator is notified that these lines are ongaged. The route over the local connecting devices (AS, LW) having been disconnected by the cut off relay T1, the circuit now -ex-1 tends from the extension station N over the leads 29, 27, wipers'36, 37, contacts 25;; 26p, back contacts 381, 391, leads28, 30, contact 358, contacts 40d) and 41a?) of the operators listening key at the private branch exchange HZ direct to the main 'exchange.-

Incoming calls from the main exchange can be dealt with by the P. B. X. operator at HZ either in known manner with plug and cord or over selecting devices as shown in the example and hereafterdescribed. A call incoming at the private branch exchange HZ from the main exchange energizes theline relay R, 'which by closing its contact 421', \establishes a circuit for the relay earth, contact 421', winding of H, battery, earth and also for the line lamp AL.. H operates and by closing its contact 43h com- U apflied earth to the wiper 23 pletes a locking circuit ove'r back contact 53;). The PI B. X. operator, by operating her listening key contacts 40ab, 4111?), 'con-, nects her instrument AbA to the calling line and ascertains that a connection is desired with the extension station N.' The operator.

over the contact 44g and over. the contact 45ab of the speaking key a circuit is closed for the relay E: earth, contact 44g, back contact 46 back contact 478, contact 45ab,

windingof E, battery, earth. E closes its.

contact 5416 thereby. switching through the line and by closing its contact 48c 1t connects up the rotary magnet of an idle exchange switch, for example AW: earth, re-

lay interrupter RU, rotary magnet D, back contact 19p, contact 486, resistance WV, battery, earth. This switch then rotates its wipers until they find the line marked by the special potential, whereupon the test relay P is operated over thecontact 496, which was likewise closed: earth, extension station key NT, winding'II of T1, wiper o f AW,

winding III of P, contact 492, resistance W, battery, earth. Contact 19;)- -is thus opened and interrupts the circuit of the rotary magnet D of the switch AW. The cut off relay T1 is also energized in the test circuit and by closing its contact 32t1 establishes the following holding circuit for itself and for the test relay P: earth, contact 32H, winding I of T1, wiper of AW, winding I of P, contact 24 contact 48e, resistance W, battery, earth; The extension sta-' tion key NT. can be released after P has operated, because the circuit for E is maintained over the earthed contact 50 9 and the contact.51e after the contact 449 has been opened. T1 also disconnects the extension station N from the local P. B. X. apparatus and at the contact 32t1 it connects up the relay T, which marks the extension line engaged. When E'operated a circuit was also established for the relay L; earth, relay interrupter LU contact 52c, winding of L, battery, earth. By the alternate opening and closing of the contacts 381, 391, ringing current is sent to the extension station N over the closed contacts 25;), 26p, wipers 36, 37 ofAW, lea ds 27, 29. Whenthe called extension station N answers, its feeding relay S operates and opens the contact 47s, thereby causing the release of the a relay E and hence also of therelay L. The relay L upon releasing disconnects the source of ringing current RQ from the line. After the contacts 486 and 496 have opened, the circuit of the cut off relay -T1 and of the test relay P is maintained over the contact 318. The line lamp is disconnected.

when the contact 53p is opened. A The extension station N and the exchange line AL are marked engaged by 335 and 34;. At the end of the conversation the hanging 111p of the receiver at the extension station de-energizes the feeding relay S, whereupon the opening of the contact 313 interrupts the circuit of T1 and P and causes the apparatus used for the call to return toits normal condition.

What I claim is:

1. In a private branch exchange, a calling line, a finder switch, a connector switch,

local telephone lines and a special'line terminating in the banks of said connector switch, means operated by the calling l ne to cause said finder to find said calling line,

means operated bysaid calling line to operate said connector to connect with one of said local lines or said-special llne, a second finder switch, an outgoing trunk to the main 4 exchange, and means responsive to the connectlon of said connector with said special line to operate said second finder to connect the calling line with said trunk.

'2. In a, private branch exchange, a calling line, a finder switch, a connector switch,

local telephone lines and a special line terminating in the banks of said connector switch, means operated by the calling line to cause said finder to find saidcalling line, means operated by said calling line to operate said connector to connect with one of said local lines or said special line, a second finder switch, an outgoing trunk to the main exchange, means responsive to the connection of said connectorwith saidspecial line to operate said second finder to connect the calling line with said trunk, and means con trolled by the operation of the second finder switch for releasing said first finderv and connector switch.

3. In a private branch exchange, an outgoing trunkxto the main exchange, a finder switch associated with said trunk-,La called line, an operators position, means con-y trolled by an operator for operating said finder to connect said line with said trunk, a connector switch, local lines and a special call terminal terminating in the banks of said connector, means for operating said connector when said line is a: calling line to connect said line with said terminal, and

means responsive to the connection of said line with said terminal for operating said finder to connect said line with said trunk.

4. In a private branch exchange, an outgoing trunk to the main exchange, a finder switch associated with said trunk, a called line, an operators position, means controlled by an operator for operating said finder to connect said line with said trunk, a connector switch, local lines and a special callfterm'inal terminating inthe banks of said connector, means for operating said.

connector when said line is a calling line to connect said line with said terminal, means responsive to the connection of said line with said terminal for operating said finder to connect sa'd line with said trunk, and, means responsive to the connection of said line with said trunk for releasing said connector.

5. In a telephone system, a calling line, a finder switch having access to said line,'a

directive switch, a non-numerical switch re- 7 sponsive-to the initiation of the call on the v means controlled by said finder switch when it finds the calling line for releasing the other switches,

7. In a telephone system, subscribers lines, a two-wa'y'trunk, a finder switch individual to said trunk and having access to said lines, and means for operating said finder to automatically hunt for and connect a line with said trunk whentheline is either calling or being called.

8; In a telephone system, subscribers lines, a two-waytrunk,'a finder switch individual to said trunk and hayin access to said lines, means for operating said finder to connect a line with said trunk when the line is either calling or being called, means controlled'over theline whenthe same is calling for marking the line as a calling line in I the bank of said finder, andmeans controlled by an operator when the line is being called for marking the line as calling in the of. said finder.

9. In a telephone system, subscribers lines, a two-way trunk, a finder switch indi= vidual to said trunk and having access to said lines, means for operating said finder bank to connect a line with said trunk when the line is either calling or being called, and means operable independent of control'over a line when the same is being called for marking such line as calling in the bank of said finder. 1

10. In a telephone system, a' calling line,

two finder switcheshavi-ng access to said line, means for starting the first finder re- ,sponsive to the'initiation of the call on the said calling'line, an automatic switch connected up by said first finder, and means for i' starting said second finder responsive to' the operation of said switch to find the callin line.

11. n a telephone system, a calling line, two finder switches having'accessto said line, means for starting the first finder re" sponsive to the initiation of the call on the I said calling line, and means responsive to a line, means for starting the first finder responsive to the initiation of the call on the said calling line, an automatic switch connected up by said first finder, means for starting said second finder to find the calling line responsive to the operation of said switch, and means responsive to the second finder -connecting with. the calling line for releasing the first finder. J v

13. In a telephone system, a callingline, two finder switches having access to said line, means for starting the first finder responsive to the initiation of the call on the said calling line, means responsive to a series of impulses transmitted from the calling line through said first finder after the "same has found the calling line for starting the said second finder to find the calling line, and means responsive tofthe second finder connecting with the calling line for releasing the first finder.

In testimony; whereof I afiix mysignature.

' ADOLF WASCHNACK. 

